OBJECTIVE: The purpose of this study was to investigate the prevalence and correlates of depression among adolescents being treated for chemical dependence. METHOD: Using the National Institute of Mental Health Diagnostic Interview Schedule, the authors interviewed 223 adolescents, aged 15-19 years, who were in residential treatment for alcohol or drug dependence diagnosed according to DSM-III-R criteria. Data on sociodemographic characteristics, school and social performance, past history, family composition, familial alcohol and drug abuse, and previous victimization of the subjects were also gathered. RESULTS: Fifty-four (24.7%) of the subjects met the DSM-III-R criteria for depression. Very few of the traditional correlates of depression discriminated depressed from nondepressed subjects, suggesting that the presence of chemical dependence overrides other predictors of depression. Only female gender, paternal psychopathology, and victimization (physical abuse, sexual abuse) emerged as important variables associated with depression. However, subjects whose onset of depression preceded their chemical dependence had different characteristics from those whose depression began after their chemical dependence. CONCLUSIONS: The prevalence of depressive illness in these chemically dependent adolescents was approximately three times that reported for nonreferred groups of similar age. This high rate of depression reflects the contributions of two distinct groups--those with primary depression and those with depression subsequent to chemical dependence--whose characteristics differed, suggesting the possibility of two pathologic processes, similar in manifestation but with different associated features and possibly with distinct etiologies. Confirmation of these findings in further research could indicate that the two forms of depression may require different treatment approaches.Abstract Teaser